[PATCH] sched_ext: Fix missing return after scx_error() in scx_dsq_move()

[PATCH] sched_ext: Fix missing return after scx_error() in scx_dsq_move()

[Cheng-Yang Chou]

When scx_bpf_dsq_move[_vtime]() is called on a task that belongs to a
different scheduler, scx_error() is invoked to flag the violation.
scx_error() schedules an asynchronous scheduler teardown via irq_work
and returns immediately, so execution falls through and the DSQ move
proceeds on a cross-scheduler task regardless, potentially corrupting
DSQ state.

Add the missing return false so the function exits right after
reporting the error, consistent with the other early-exit checks in
the same function (e.g. scx_vet_enq_flags() failure at the top).

Fixes: bb4d9fd55158 ("sched_ext: scx_dsq_move() should validate the task belongs to the right scheduler")
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 551bfb99157d..a5d8871ac865 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -8094,6 +8094,7 @@ static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit,
 	if (unlikely(!scx_task_on_sched(sch, p))) {
 		scx_error(sch, "scx_bpf_dsq_move[_vtime]() on %s[%d] but the task belongs to a different scheduler",
 			  p->comm, p->pid);
+		return false;
 	}
 
 	/*
-- 
2.48.1

Re: [PATCH] sched_ext: Fix missing return after scx_error() in scx_dsq_move()

[Tejun Heo]

Applied to sched_ext/for-7.1.

Thanks.

-- 
tejun